1. Field of the Invention
The present invention relates to a light measuring apparatus, particularly presenting a circuit that improves the response characteristics of the apparatus.
2. Description of the Prior Art
A light measuring circuit for producing an electrical signal in accordance with the brightness to be measured, presenting an operational amplifier, a feed back path and a photo voltaic cell is already known.
However, in such a light measuring circuit it takes considerable time before the output of the measuring circuit is stabilized when measuring low light levels even if a photo voltaic cell is adapted as the light sensitive element, which is very inconvenient. Namely, when the light measuring circuit is activated and the photo voltaic cell produces an electrical signal, the stray capacitance existing in the operational amplifier is charged with this electrical signal or the charge present in the stray capacitance is discharged, so that especially when the light to be measured is suddenly reduced in intensity it takes considerable time before the output of the above mentioned light measuring circuit is stabilized, which is very inconvenient.